Showing papers by "Waseda University published in 1985"

The double scroll

Abstract: A detailed analysis is given of the geometric structure of a chaotic attractor observed from an extremely simple autonomous electrical circuit. It is third order, reciprocal, and has only one nonlinear element: a 3-segment piecewise-linear resistor. Extensive laboratory measurements from this circuit and a detailed geometrical analysis and computer simulation reveal the following rather intricate "anatomy" of the associated strange attractor. In addition to a microscopically infinite sheet-like composition the attractor has a macroscopic "double-scroll" structure, i.e., two sheetlike objects are curled up together into spiral forms with infinitely many rotations. (See frontispiece.) The chaotic nature of this circuit is further confirmed by calculating its associated Lyapunov exponents and Lyapunov dimension. The double-scroll attractor has one positive, one zero and one negative Lyapunov exponent. The Lyapunov dimension turns out to be a fractal between 2 and 3 which agrees with the observed structures. The power spectra of the three associated state variables obtained by both measurement and computer simulation show a continuous broad spectrum typical of chaotic systems.

The Realization of Dynamic Walking by the Biped Walking Robot WL-10 RD

Abstract: 本研究は, 外乱の無い平担路において2足歩行ロボットWL-10RDによる動歩行を実現することを目的とする.一般に, 1歩行周期は単脚支持相と立脚切換相という2つの相に分けられる.この両相において動力学的動作が行われているものが動歩行であると考えられる.本論文では動歩行の制御方式として次のような方式を提案する.すなわち, 単脚支持相においては設定歩行パターンを用いたプログラム制御を行い, 立脚切換相においては切換状況に応じて足首部のトルクと機械インピーダンスを可変とするシーケンス制御を行う.実際には, 単脚支持相においては, 3次元動力学解析により, ZMP (Zero Moment Point) が支持脚の足底面内にあるように, 設定歩行パターンを作成する.立脚切換相においては, これをさらに4つの相に分割し, 脚接地時の衝撃を緩和しながら重心が後脚から前脚側に切換わるように, 足首部トルクと機械インピーダンスを適切に定める.このようにしてWL-10RDによる動・完全歩行が実現した.歩行実験の結果, 歩行時間は歩幅40 [cm] で1歩1.5 [sec] が達成された.

Parallel processing of robot-arm control computation on a multimicroprocessor system

Abstract: A parallel-processing scheme is described for robot-arm control computation on any number of parallel processors. The scheme employs two multiprocessor scheduling algorithms called, respectively, depth first/implicit heuristic search (DF/IHS) and critical path/most immediate successors first (CP/MISF); these were recently developed by the authors. The scheme is applied to the parallel processing of dynamic control computation for the Stanford manipulator. In particular, the proposed algorithms are applied to the computation of the Newton-Euler equations of motion for the Stanford manipulator and implemented on a multimicroprocessor system. The test result was so successful that the use of six processor pairs in parallel could attain the processing time of 5.37 ms. It is also shown that the proposed parallel-processing scheme is applicable to an arbitrary number of processors.

Chaos and Husimi distribution function in quantum mechanics.

Abstract: We study the correspondence between quantum and classical dynamics with Wigner and Husimi distribution functions, respectively. The nature of quantum-mechanical regular and irregular behaviors is discussed with the use of Wigner and Husimi distribution functions. By numerical studies of the chaotic state, the Husimi distribution function is found to be a better representation than the Wigner distribution function, because coarse graining is usually involved implicitly in an observational process using the Wigner distribution function.

Improvement of Radiation Resistance of Pure Silica Core Fibers by Hydrogen Treatment

Abstract: A pure silica core fiber with glass cladding is known to produce larger absorption in the visible wavelength region under γ-ray irradiation than a similar fiber with silicone cladding. This absorption is a serious problem, especially in image-guiding fibers used in radiation environments such as in nuclear power plants. The absorption is attributed to the formation of defect centers such as non-bridging oxygen hole centers and E' centers induced by bond scission. A new and simple method of hydrogen treatment to improve the radiation resistance of an optical fiber with a pure silica core has been proposed. Post-treatment by this method can significantly reduce existing radiation-induced absorption, while preliminary treatment can suppress the increase of the radiation-induced absorption.

Some ways to increase flexibility in manufacturing systems

Abstract: In recent years, many flexible manufacturing systems have been or are being developed. FMS is important in order to adapt to severe changes in market and technology and also to increase productivity. In this paper, the evaluation variables of flexibility are proposed and factors improving the flexibility of single-stage production systems with different characters are discussed. However, most production systems are multi-stage mixed type systems. This paper also points out the characteristics of the amplification of multi-stage production systems as one of the important factors affecting the flexibility and productivity of the systems. Furthermore, some ways of reducing the amplification by the ordering systems are also presented. The multi-stage ordering models discussed here are simplified, neglecting the characteristics of the single production systems which make up total multi-stage production systems and neglecting parameters concerning transportation and material flows. The flexible manufac...

Does actin bind to the ends of thin filaments in skeletal muscle

Abstract: We examined whether or not purified actin binds to the ends of thin filaments in rabbit skeletal myofibrils. Phase-contrast, fluorescence, and electron microscopic observations revealed that actin does not bind to the ends of thin filaments of intact myofibrils. However, in I-Z-I brushes prepared by dissolving thick filaments at high ionic strength, marked binding of actin to the free ends, i.e., the pointed ends, of thin filaments was observed when actin was added at an early phase of polymerization. As the polymerization of actin proceeded, the binding efficiency decreased. The critical actin concentration for this binding was higher than that for polymerization in solution. The binding of G-actin was not observed at low ionic strength. On the basis of these results, we suggest that a particular structure suppressing the binding of actin is present at the free ends of thin filaments in intact myofibrils and that a part of the end structure population is eliminated or modified at high ionic strength so that further binding of actin becomes possible. The myofibril and I-Z-I brush appear to be useful systems for studies aimed at elucidating the organizational mechanisms of actin filaments in vivo.

Lamprey erythrocytes lack glycoproteins and anion transport

Abstract: 1. 1. Methods were developed to measure the anion transport across the erythrocyte membrane using electrodes. 2. 2. Unlike mammalian erythrocytes, lamprey erythrocytes lack the anion transport phenomena. 3. 3. Results of SDS gel electrophoresis indicated that the membrane of lamprey erythrocyte does not contain two types of glycoproteins which are found in other species; namely, Band 3, which is known to transport anions, and glycophorin A.

Practical multiprocessor scheduling algorithms for efficient parallel processing

Abstract: This paper describes practical optimization/approximation algorithms for scheduling a set of partially ordered computational tasks with different processing times onto a multiprocessor system so that the schedule length is minimized. Since this problem belongs to the class of “strong” NP hard problems, we must eliminate the possibility of constructing not only pseudopolynomial time optimization algorithms, but also fully polynomial time approximation schemes unless P = NP. This paper proposes a heuristic algorithm CP/MISF (Critical Path/Most Immediate Successors First) and an optimization/approximation algorithm DF/IHS (Depth First/ Implicit Heuristic Search). DF/IHS is an excellent scheduling method which can reduce markedly the space complexity and average computation time by combining the branch-and-bound method with CP/MISF; it allows us to solve very large-scale problems with a few hundred tasks.

Scintillation yields by relativistic heavy ions and the relation between ionization and scintillation in liquid argon

Abstract: Scintillation yields per unit energy deposited by relativistic heavy ions in liquid argon have been measured. They are (1.41 ± 0.07) for 613 MeV/n Ne ions and (1.39 ± 0.07) for 705 MeV/n Fe ions, if the value is normalized to unity for 5.3 MeV alpha particles. These results show that the scintillation intensity for relativistic heavy ions in liquid argon is proportional to the deposited energy, that is, to Z12, where Z1 is the nuclear charge of heavy ions. Furthermore, the variation of ionization and scintillation in liquid argon has been investigated as a function of electric field using relativistic Ne and Fe ions. It is shown that a linear combination of ionization signal I and scintillation signal S, I + aS, is proportional to the deposited energy, independently of electric field strength and types of incident particles. This suggests that if we use both signals, we may construct a massive calorimeter that can be used for nuclear reactions induced by relativistic heavy ions.

Realization of Plane Walking by the Biped Walking Robot WL-10R

Abstract: The purpose of this study is to accomplish plane walking by a hydraulic-powered biped walking robot on a flat floor. Plane walking consists of three types of fundamental pattern walkings: straight walking, sideway walking and turning. The control method is a program control with a preset walking pattern. In forward walking the gait is a quasi-dynamic walking. We propose a new quasi-dynamic walking-control method as follows: change-over phase is divided into four phases according to the floor contact of soles, a walking pattern is designed by computer simulation and the output to a machine model is interpolated with a parabola function. In the other walkings the gaits are static walkings which are statically stable through all walking cycles. The model WL-10R is an anthropomorphic biped walking robot with 12 degrees of freedom driven by an electro-hydro servo mechanism. Additionally, WL-10R has a control device on its upper body. As a result of experiments, smooth and stable quasi-dynamic forward walking is achieved; the walking time is about 4.8s with 45cm stride. Stable static plane walkings are realized.

Seasonal Changes in Photosynthesis of Four Understory Herbs in Deciduous Forests

Abstract: Seasonal patterns of photosynthesis and respiration of single leaves of four understory perennial herbs in deciduous forests were investigated in relation to their leaf growth and light conditions on the forest floor.Anemone flaccida shows rapid growth of leaf area and high rates of gross photosynthesis at light saturation (Psat) in its early stage of development. Its photosynthetic activity is restricted to a brief period of high light intensity before the closure of overstory canopies.Disporum smilacinum possesses light-photosynthesis curves of the shade-leaf type throughout its whole growing period. A shading experiment has shown that this plant is low-light adapted and can utilize weak light efficiently. The light-photosynthesis curve ofSyneilesis palmata shifts from the sun-leaf type to the shade-leaf type in response to the seasonal change of light regime on the forest floor. Evergreen leaves ofPyrola japonica have three year longevity, and light-photosynthesis curves of the shade-leaf type. They maintain some photosynthetic activity even in late autumn and winter.

Species diversity and primary productivity inMiscanthus sinensis grasslands

Abstract: In an old field grassland dominated byMiscanthus sinensis Anderss. the community structures, phytomass, dominance ofM. sinensis and species diversity were measured. Species and life form composition of the stand were characterized by higher percentages of therophytes, woody and shrubby species, liana and alien species. From May so September in 1982, all the aboveground parts were harvested from each of the four quadrats (2 m×2 m) once a month. Seasonal peak of aboveground phytomass, in September, was 1027 g d.w.m−2 to whichM. sinensis contributed as much as 96.5%. With the progress of the growing season,M. sinensis became increasingly important both in stand phytomass and in dominance, whereas species diversity based on the dry weight contributions of constituent species decreased. Our analysis of these seasonal trends showed that the diversity was largely a function of dominance of the most important species, rather than that of stand phytomass or productivity. The simultaneous measurements of 20 quadrats in late August 1983, also supported the above conclusion.

Liposome-embedded iron-porphyrins as an artificial oxygen-carrier.

Abstract: In a living body a red blood cell serves to transport molecular oxygen. The red blood cell contains hemoglobin (Hb), with the oxygen-transporting function, which is encapsulated within the cell membrane. As the model of this red blood cell, Hb has been artificially encapsulated with a synthetic polymer such as nylon’ or with a phospholipid liposome.’ They were an attempt to prepare artificial oxygen carriers as blood substitutes. The present author embedded a synthetic iron-porphyrin (heme) complex, which is the analogous compound of the oxygen-binding site (protoheme) of Hb, in the phospholipid bilayer of liposomes, as illustrated in SCHEME 1: this liposome-embedded heme transports oxygen under physiological conditions. Hb binds molecular oxygen in response to oxygen pressure. However, if the protoheme complex is isolated from the globin protein and exposed to oxygen, the protoheme complex is immediately and irreversibly oxidized and it does not act as an oxygen carrier. Much research has been directed to mimic the oxygen carrier like Hb by synthesizing various modified heme d e r i ~ a t i v e q ~ which is the elegant steric modification of porphyrin: porphyrins have been replaced with a “cyclophane group”,6-‘ ’ “picket fence g r o ~ p ” , ’ ~ ~ ’ ~ ‘‘crown ether g r ~ u p ” , ’ ~ “cyclodextrin g r o ~ p ” , ’ ~ , ’ ~ etc. These synthetic hemes have been successful in oxygen binding reversibly in organic solvents and solid states, but in aqueous media they have been irreversibly oxidized. The reasons for the oxygen-binding by Hb are considered to be as follows.” (1) The heme is dispersed and diluted to suppress the irreversible oxidation via a p-dioxo dimer (Equation 2). (2) The heme is surrounded by the hydrophobic environment, causing the proton-driven oxidation (Equation 3) to be retarded.

Spatial distribution readout system of thermoluminescence sheets

Abstract: We have developed a spatial distribution readout system of thermoluminescence (Tl) sheets, which realizes in more detail the two dimensional (2-D) photon counting. The thermal fading effect of the Tl sheet has been investigated and the cosmic ray flux at 16000 m altitude causing background in the Tl sheet has been obtained by the 2-D photon counting.

Ohzora high energy particle observations

Abstract: Observations of fluxes and energy spectra of electrons (0.19-3.2MeV) and protons (0.64-35MeV) by OHZORA satellite are reported. The results obtained during March 14-June 22, 1984 are discussed in this paper. The maximum fluxes of electrons and protons are observed in the South Atlantic Anomaly and the auroral zones. Narrow peaks of counting rate in “the midlatitude zone” of L=1.6 are observed over the south Pacific Ocean and Mexico, and the pitch angle distribution of the particles shows that these particles are geomagnetically trapped. Temporarily intensive proton and He ion fluxes at the north polar cap region are observed, and their particle energy spectrum shows that solar flare particles are injected into the polar cap.

Design of polymer membrane with permselectivity for water–ethanol mixture. II. Preparation of crosslinked poly(methyl acrylate) membrane with diethylene triamine and its permselectivity

Abstract: In order to permeate water from a water–ethanol mixture by pervaporation on the basis of the difference in solubility between two components toward a polymer membrane, polymer membrane having polar group, poly(methyl acrylate) (PMA) membrane crosslinked with diethylene triamine (DETA) was prepared. The permselectivity of the membrane was investigated with attention to the feed composition of water–ethanol mixture and the effect of introduction of DETA into the membrane. It is found that water was permeated through PMA–DETA crosslinked membrane preferentially in all ranges of feed composition, the highest permselectivity being observed at 25% ethanol aqueous solution. Moreover, the pervaporation rate of water was found to depend on the ratio of DETA introduction into the membrane. When the ratio of introduction into the membrane was 0.144, water was permeated through the membrane from 25% ethanol aqueous solution at a rate of 1.26 × 10−1 g m/m2 h. These results can be explained by high diffusivity of the membrane due to the low glass transition temperature of PMA and permeation of water through polar DETA moiety in the membrane.

Three phase fluidized bed bioreactor process

Abstract: A three phase fluidized bed water purifying process comprises purifying effluents in a three phase fluidized bed (1) composed of solid particles (4), an effluent, and a gas (13) in fluidized state, the solid particles being made by mixing a binder with an inorganic material based on aluminium silicate, granulating the resulting mixture, and firing the granules to sinter them. Such a process permits the purification of effluent for a long period of time without oxygen deficiency.

Autonomic Limb Control of the Information Processing Robot

Abstract: これからのロボットは, ‘力作業’だけでなく‘情報作業’をも行う能力をもつ必要がある.そこでこの研究では, 鍵盤楽器演奏可能な人間形知能ロボットを開発することにより, 情報作業に必要となる機能である巧緻性, 高速性, 高度の知的能力などを実現することを目的としている.本論文では, そのためのロボットの4肢構成とその制御に焦点をおき開発した鍵盤楽器演奏ロボット‘WABOT-2’の運動系について述ベる.このロボットは, 5本指をもつ両手と, ペダル操作用両足の4肢からなり, その自由度は合計で50である.このような多自由度ロボットは他に例がなく, その制御法が問題となり, また自律制御を行ううえでは, 楽譜情報から4肢の軌道を決定する方法が重要となる.以上のような制御問題を解決するために, WABOT-2運動系では53個のマイクロプロセッサからなる3重階層構造のコンピュータシステムを構成した.その上位コンピュータシステムは, 楽譜情報処理を担当し, 3種類に分類した知識, (1) 作業対象物, (2) 作業内容, (3) ロボット機構部仕様をもとに, 視覚系より転送される楽譜データから運指・手首位置の決定, 指・腕・足の各関節角度計算を行う.中位コンピュータシステムは, 上位コンピュータシステムで計算された軌道をもとに, 制御用データを下位コンピュータシステムへ出力し, また必要に応じて各自由度の状態をモニタすることにより協調制御を行う.そして, 下位コンピュータシステムは, 各自由度に1チップマイクロコンピュータが置かれており, ソフトウエアサーボをかけている.このようなコンピュータシステムにより, 50自由度の効率良い制御を実現した.以上の結果, WABOT-2は電子オルガン中級程度の曲について, 楽譜情報を入力するだけで自動的に演奏が可能となった.